The following description is provided to assist the understanding of the reader. None of the information provided or references cited is admitted to be prior art to the present technology.
Demand is increasing worldwide for reliable, efficient, and low-cost air treatment systems in confined spaces. Air contaminants include volatile organic compounds (VOCs), inorganic/organic particulates, and biological particulates such as bacteria, fungi (mold), and various other biological contaminants (including viruses). Many filtration strategies exist for purifying air, yet they suffer from various drawbacks.
Physical filtration strategies remove most particulates, but have little effect on VOCs. They can also serve as a breeding ground for microorganisms, which compromise the flow rate of air through the filter.
Electrostatic filtration strategies improve on basic physical filtration without further restricting airflow. However, energy is required to charge the filter. Importantly, electrostatic filtration strategies do not address VOCs and they do not kill bacteria. They can therefore serve as a breeding ground for microorganisms.
Photochemical filters generally include TiO2 as an agent to generate singlet oxygen, which can kill microorganisms. While generally effective, and despite the TiO2 having a long lifetime, the lifetime of the active species of the filter, e.g. the singlet oxygen, is very short. In addition, favorable TiO2 kinetics are limited to a small number of surfaces.
Active Chemical filtration is effective, but the lifetime may be too short. In addition, the filter may be expensive and/or burdensome to replace or recharge. Other problems are that the active chemical can be a health hazard (e.g. ozone), and/or very slow kinetics (e.g. peroxymonosulfate).